As is known, railroad cars have been used to transport everything from commerce, such as goods and products, to military hardware, such as weapons and supplies, to people all around the country and all around the world. In fact, railway transportation is so important that a large portion of the economy relies on the railways as a mode of transportation to safely transport people between destinations and to safely deliver goods and materials to manufacturers and distributors. As such, any disruption in this service creates a ripple effect that can be felt throughout the economy. Thus, in order to avoid disruption of the railway service as well as to maintain a safe environment for railroad personnel and railroad passengers, it is essential that all key components of the railroad cars are maintained in safe and proper working condition. It is important that key components of the railroad cars are monitored to identify any existing conditions or potential conditions that might cause a failure of a railroad car component resulting in a loss of life or in the possible damage to the train and its cargo, as well as a failure of the train to meet its intended delivery schedule.
In order to accomplish this task, detector systems are typically positioned along the rails to monitor and detect the operational condition of the railroad cars as they past the detectors. Each time a train passes these detector systems, typically classified as Wayside Equipment, the detector systems communicate information responsive to the operational condition of the railroad car to an operational office via a phone line or to the train crew via a VHF radio that interfaces with the Wayside Equipment over the “dispatch channel” used for that territory. The dispatch channel is the communications channel (i.e. frequency) that the locomotive crew has their VHF radio tuned to so that they can hear directions from the railroad dispatcher. For example, one type of detector system currently in use is a Hot Bearing/Hot Wheel (HB/HW) detector system. Referring to FIG. 1, a Hot Bearing/Hot Wheel (HB/HW) detector system 100 in accordance with the prior art is shown, wherein the HB/HW detector system 100 includes at least one detector apparatus 102 that is communicated with a central office 104 and with the train crew via a voice radio 106. The detector apparatus 102 analyzes the condition of the bearings and/or wheels of the passing railcars (e.g. for “hot spots”) and broadcasts any detected defects to the train crew via the voice radio 106. Any additional alarms and/or data may also be communicated back to a central office 104. Additionally, various other types of detectors may be connected to the unit, such as a dragging equipment detector or other detectors that typically provide simple contact closures.
Another type of detector system currently in use is a “talker system.” Referring to FIG. 2, a “talker system” 200, in accordance with the prior art, is a defect detector system 200 that includes one or more detection devices 202, wherein the detection devices 202 typically provide contact closures when a defect is detected. The defect unit then reports the defect to the train crew typically by broadcasting the alarm over the voice radio 106. As above, any additional alarms and/or data may also be communicated back to the central office 104. This type of “talker system” 200 differs from that in FIG. 1 in that the “talker system” does not typically include a hot bearing or hot wheel scanner. Still another type of detector system currently in use includes an HB/HW detector system 100 that is integrated with an AEI Tag Reading system. Referring to FIG. 3, HB/HW detector system 100 integrated with an AEI Tag Reading system 108 in accordance with the prior art is shown, wherein AEI tag readers obtain car ID information by reading an ID tag that is affixed to each railcar. This car ID information can then be used to better locate a defect, such as a hot bearing or hot wheel. Additionally, the car ID information could be used to more efficiently locate a defect rather than trying to identify the location of the defect by counting the axles. Moreover, actual scanned heat data for each wheel bearing on a railcar can be associated with a particular railcar to allow better analysis of the railcar bearings to order to better predict when they are going to fail. This allows bearings that have typically higher temperatures to be tracked even though they are below the alarm threshold.
Referring to FIG. 4, current detector systems commonly have two methods or links for communicating information. One communication path is to transmit data to a central or local office and may be accomplished via any established network, including telephone lines, wireless networks, cell phones, Ethernets, etc. Data can be sent to the office locations and can include everything from the most recent detection information to the entire train log with complete thermal data collected from the train, to alarm and/or diagnostic data. However, in alarm situations, this “data” link is not adequate to identify an emergency situation and take necessary action to prevent a possible disaster. Another communication path is to transmit data directly to the onboard train crew. This is typically accomplished by the detectors transmitting a synthesized voice or recorded voice message via a VHF voice radio as the train passes, wherein the message includes the name of the railroad, the location of the detector, the type of detector and the Alarm status (i.e. summary result of the train analyzed . . . such as “No Defects Detected”). Moreover, alarm messages may typically contain additional information, such as side and axle location for Hot Wheel or Hot Bearing detectors. This broadcast can take any where from 10 to 45 seconds even if there are no alarms.
Referring again to FIG. 4, a typical interface between the defect detector unit and a voice radio in accordance with the prior art is shown. To effect a radio transmission, the defect detector unit activates a “Push-To-Talk” or similar interface line of a standard radio to put the radio into transmit mode, thus enabling the radio microphone or other modulation input. The defect detector unit then plays back the appropriate recorded or synthesized voice message and applies the message to the radio modulation input. This “voice” message is then transmitted from the wayside radio to its intended destination. The wayside radio is configured to monitor a main or “road” frequency used by the dispatcher to communicate to the onboard train crew via the radio installed on the locomotive. The onboard train crew will then hear the broadcast message across the radio speaker and appropriate action will be taken if required. It should be appreciated that some radios have a “busy” indication (identified as “busy” on the block diagram of FIG. 4), which is an output from the radio that indicates that the radio channel is busy. The defect detector system will use this to inhibit radio broadcast until the channel is clear. Moreover, some systems can be equipped with a “re-broadcast” function. If the on-board train crew did not hear or understand a radio broadcast, this function allows the train crew operator to transmit a sequence of Dual Tone Multi-Frequency (DTMF) tones, as capable from standard locomotive radios, to the wayside radio to trigger a re-broadcast signal to the defect detector unit causing the defect detector unit to repeat the last radio transmission.
One reason that radio broadcasting is used is that it currently provides the quickest and easiest method to ensure that proper action is taken in an emergency situation. For example, each time the train passes the defect detector equipment, the broadcast allows the crew the opportunity to validate the proper operation of the equipment, including the radio system. In fact, on many railroads, the train crews are required to have their radios set to monitor the broadcast channels from the dispatch in order to “hear” the broadcast and to validate that the detector and radio system are working. Thus, when the train passes the defect detector equipment, the crew verifies that they heard the defect detector equipment broadcast a recorded message. Upon hearing this message, the crew validates that the defect detector system (including the radio system) is operating normally. If the crew receives a message from the defect detector system that indicates a malfunction on the railroad train, the crew then takes appropriate action. For example, the operational status information may include wheel axle numbers and position (left/right), so that in the event that HOT bearing is detected, the crew could be directed to the axle location on the train for inspection. In fact, most operating rules dictate that if a Hot Bearing Alarm is identified, the train needs to be stopped and the bearing inspected to determine if the car needs to be cut out or if safe to proceed.
One disadvantage with the current system is that due to the need to more closely monitor railroad equipment along critical rail lines, the number of defect detectors installed along the rails has increased substantially. Unfortunately, this increase in the number of detectors installed along the wayside has had a negative impact on the amount of available “Air Time” a dispatcher has to communicate with the train crews. In fact, more and more of the available dispatch radio channel bandwidth is being used up and as such dispatchers are not able get airtime with all of the detectors broadcasting. For example, the defect detector equipment is typically set to broadcast directly to the crews each time the train passes, not just when the defect detector equipment has detected a problem. The increased number of defect detectors (e.g. every 10 miles instead of every 50 miles), the increased miles of double track lines and an increase in train traffic all cause an increase in the number of radio transmissions (the typical normal transmission takes about 30 second of air time) which results in a reduced amount of available air time for the dispatcher to talk to the trains.
This “radio congestion” is undesirable due for a number of reasons. First, the increased radio traffic may result in messages being transmitted well after the train has passed the defect detector equipment. Second, the increased radio traffic may result in lost or partial messages. If simultaneous message transmissions are occurring the train crew may only receive a portion of the message or the train crew may not hear the message at all. In an attempt to reduce the number of radio transmissions from the defect detector radios, some railroads have gone to exception reporting. This is where the systems no longer broadcast messages to each passing train, but only to those that have an alarm condition. Although this has been successful in reducing the number of radio transmissions, it creates a secondary problem in that, as discussed hereinabove, the broadcast of non-alarm messages are used to validate the proper operation of the system where engine crews report detector locations that do not broadcast as they pass as defective so that they may be repaired.